Reproduction Outside of Species?

I grew up with the understanding that it was impossible to breed between different species. However I've seen this contradicted by hybrids among the four Big Cats (Lion, Tiger, Leopard and Panther) who can all crossbreed.





So, is the rule that you have to be of the same genus to reproduce and not genus? And if so, would it be possible for members of the Homo genus to have crossbred as well (i.e,. a Neanderthal and an early Modern Human)?





Thanks!

Reproduction Outside of Species?
Great question. Alot of folks define a species as a group of organisms that can interbreed. There are however examples where this definition fails. I'm not familiar with your example but if its true, there ya go.





So what is a species or for that matter a genus? These are terms that WE made up to help us begin sorting and classifying all of life. While the system is VERY useful for naming it can sometimes get us in trouble. Life doesn't conform to the definitions of our terms!





So, then what is the barrier between two organisms from reproducing? - It's GENETIC!





Durring mitosis, chromosomes are replicated and aligned along the metaphase plate. If the genome of two organisms is sufficiently similar to allow the chromosomes to align (and begin crossing over) such that each daughter cell gets an intact copy of the genome.. then the two organisms can sexually reproduce.





IF the genomes are sufficiently different and chromosomal segregation fails - then the two organisms can't have sex.





Another barrier I've thought about is binding between ZP3 and the ZP3 receptor but I don't have any data on this but someone else might.





So, answer the question already right? Could neanderthal and early homo sapians interbreed? Only if their chromosomal structure was similar enough to align and segregate properly during mitosis. Note that most of the anthropoligcal data suggests that the two groups DID interbreed.
Reply:Very cool. I'm glad you got the most votes. I didn't mean for it to go up for voting between you and everyone else.





But this goes to show that too many Yahoo! Answers users just vote for the sake of getting a point (going by how close #1 was to beating you). Report It

Reply:Ligers and Tigons (name differs depending on which parent is which) are common enough in zoos but not in the wild, but they are sufficiently common enough in captivity to know that they ARE fertile, this is probably because all members of the family have the same number of Chromosomes.





Mules are generally infertile beacuse they have an odd number of chromosmes so cannot split them equally to produce vaible sex cells., however, there is one case of a mule succesfully fertilizing a donkey but this may be due to a chromosomal "defect" in the first place.





That have also been cases in the wild of grizzly and polar bears cross-breeding.





Species are not supposed to be able to interbreed but it depends if they've evolved sufficiently to be totally distinct including on a genetic level. The common ancestor of all cats maybe only a few million years distant and therefore tIgers and lions at least are not genetically different enough as yet to not be able to have offspring together.
Reply:I think it can happen. Because if they can cross breed donkey and the horse and make ponies y cant they since the all belong to Homo
Reply:the definition of species is not so concrete as people think, however most would agree that a species must be able to reproduce .


ligres, tions, mules etc are infertile.


there are pre and post mating mechanisms which prevent these hybrids from reproducing, and this is what is meant when people say it is impossible to breed between different species.





i.e, even if the offspring of crosses are viable, they are usually not fertile.
Reply:Many plants occasionally cross with different species within the same genus (oaks, for example). Others reproduce by cloning (hawthorns, for example), so how do you apply the definition?


Some critters don't normally cross because they live in different locations and/or have different behaviors so we call them separate species. But when brought together under different conditions (say, at a zoo), they might occassionally mate and produce offspring.


That shows us that our definition of species is somewhat arbitrary, though very convenient. Some plants--and animals for that matter--may not have read the book and don't fit the definition :-).


This is consistent with our understanding of evolution. Many species have completely separated from others and there is no interbreeding at all. But some have not separated completely, or are incompletely separated, so they can cross. Varieties are populations that are somewhat distinct, but not distinct enough to be called separate species. They may become separate species in the future, but not necessarily.


Back to the oak example: oaks have separated into two main groups--the red oak group and the white oak group all in the same genus, Quercus. Members of the red oak group can hybridize within the group, and members of the white oak group can hybridize. For example, white oak and burr oak form a hybrid.


As to the question about Neanderthals, the final answer is not in, but it is certainly possible, and some anthropologists think it likely.
Reply:About natural limits, I do not know. However, the species barrier is down. It is now possible to include traits from just about anything into any other life-form.





Perhaps if that should interest you - a search for species barrier down might do the trick.
Reply:The answer is, if you have the same # of chromosomes it's likely. There are other things that matter, too, but if there are a different # of chromosomes then it's not possible. I don't know how many chromosomes all the different species have though, so I can't tell you if the homos interbred a long time ago. I know humans have 46 though.
Reply:Yes, none who qualified is prepared to mention that there are differences in the human species. Geneticists refuse to admit it because it would just cause more trouble but it will leak out, there are slightly different , well not species of humans but origins of genes , and you would be suprised who.
Reply:The traditional definition of a species specifies that they can breed within, but not outside of their group.





Of course, with the wonderful diversity we have on our beautiful planet, there are situations which stretch the rules a bit. Take for example the mule - a combination of horse and donkey, or the liger (lion and tiger) not to mention a whole array of plants...





The main thing is 'viability', and very often these species cross-over organisms are reproductively infertile, or their offspring are.





The problem when considering modern humans and Neanderthals, would be time. I think Homo Habilis and Neanderthalis cross bred, but I'm not sure.